Water from a water heater is often hotter than desirable for its end use at a plumbing fixture. For example, heating water to a high temperature (e.g., above 140° F.) can be important to avoid growth of bacteria during long-term storage of water at lukewarm temperatures (e.g., 105-115° F.) that may be more appropriate for end use. Further, although extremely hot water temperatures may be useful in some appliances in which the water does not directly interface with a person, such as a dishwasher, it is problematic for water at such high temperatures to directly contact the end user in other uses, such as faucets for washing.
Accordingly, many faucet and plumbing fixture setups utilize devices that control or regulate the temperature of the output flow of mixed water received from a hot and a cold input. One such temperature control device is a thermostatic mixing valve. A thermostatic mixing valve blends hot water with cold water to produce tempered hot water, conventionally prior to the introduction of the tempered hot water to the faucet or plumbing fixture in the first instance. Typically, the thermostatic mixing valve is plumbed to receive hot and cold water inputs and output tempered hot water for provision to the hot water connection of the faucet or other plumbing fixture. Separately, cold water is provided to the cold water inlet of the faucet. With this arrangement, even if the user sets the faucet or plumbing fixture to its hottest setting (e.g., opening the hot valve entirely while the cold valve remains closed), the use of the thermostatic mixing valve can limit the maximum output temperature of the faucet or plumbing fixture to that of the tempered hot water and ensure a constant, safe water temperature to prevent thermal shock or scalding of a user.
Unfortunately, to reduce the expense and time associated with installing a faucet or plumbing fixture, many installations lack a thermostatic mixing valve prior to the provision of water to the faucet. Further, some plumbing codes dictate when a thermostatic mixing valve must be used, which vary city to city and state to state.